“Sean joined us in our first year and has been with us for three tough but rewarding seasons,” said team principal Dave Brailsford. “After a long career in professional cycling, he has told us that he wants to move on, for purely personal reasons.

“Sean has been a great support to the riders on the road and a valuable colleague to us all. We wish him the best for the next step in his life.” The team said that he plans to retire from cycling after three decades in the sport.

In the wake of the Lance Armstrong/US Postal Service investigation, Team Sky said that it would take steps to ensure that everyone who worked for the team, riders and staff, had no previous connection with any doping practices.

It is understood that if people make admissions, they will be supported – presumably with a settlement – while they seek work elsewhere. However if individuals deny any connection to past doping and are subsequently shown not to have told the truth, they will be immediately fired.

Yates tested positive during the 1989 Tour of Belgium but was ultimately not sanctioned due to technical reasons.

He competed with Armstrong for several seasons and was also a directeur sportif on the Discovery Channel and Astana teams. He insisted recently that he saw no signs of doping on those squads, despite witness statements saying that the US Postal Service/Discovery Channel structure was one where doping was not only tolerated but actually encouraged.

The Sky Procycling team is yet to comment on reports that Steven de Jongh is also leaving his directeur sportif position.